The present invention relates, in general, to liquid dispensing systems, and more particularly, to non-venting hazardous material liquid dispensing systems.
The semiconductor processing industry, as well as others, constantly faces the challenge of health and environmental requirements relating to handling hazardous materials. For example, the Federal Clean Air Act of 1990 places strict requirements on controlling emissions of volatile organic components (VCOs). Typically, permits must be obtained from county or state authorities as changes occur at manufacturing locations which generate VCOs. Furthermore, solvent thermal decomposition units installed to abate hydrocarbon VOC emissions are costly at approximately $1,000 per cubic-feet-per-minute capacity. In addition to federal and state requirements, manufacturers must be sensitive to local community and neighborhood demands for destruction of odors and fumes from semiconductor manufacturing plants.
Under present federal and state requirements, expensive permitting is required for equipment installation or location movement involving hazardous materials. Costs include not only costs of permitting, but costs for hours of professional engineering needed to specify and quantify systems, and to prepare compliance applications and forms. Costs may further include those associated with months of delays waiting for permits to be issued, such as loss of business.
In the past, gallon supply bottles have been used to fill process tools with hazardous material liquids such as VCO solvent type materials. Unfortunately, the gallon supply bottles give rise to many problems. For example, disposal of the bottles themselves, even after they are empty, requires elaborate environmentally safe methods. Additionally, filling tools with supply bottles open to the atmosphere creates vapors and odors in production areas which can effect yields.
As an alternative to gallon bottles open to the atmosphere, refillable vessels have been used in production process tools as single vessels with quick disconnects in line with the tool liquid supply line. Removal of these vessels require a process tool shutdown which severely lowers productivity of process tool. Furthermore, the conventional use of refillable vessels requires that a vessel be replaced in a system before the vessel goes empty, thereby wasting chemicals. Alternatively, the vessel could be replaced after the vessel is empty. However, gas used to drive the chemicals must first be purged away. Any purging must be vented and requires permitting and environmental abatement by some means. If pumping is used then tools must be shut down as vessels are replaced, and purging sequences must be done again.
Hence, a need exists for a non-venting automated liquid transfer system which can run semiconductor processing tools continuously while vessel supply changeouts occur. Furthermore, a need exists for a non-venting system which does not require environmental air permits, thus alleviating cost and time delays associated with conventional methods.